Multi-capillary array electrophoresis device

ABSTRACT

An electrophoresis apparatus includes a multi-capillary array having a liquid or solid disposed between the capillaries of the array. The liquid or solid exhibits a refractive index higher than that of air and less than that of water and reduces the amount of laser beams scattered by the capillaries. Also provided are methods of adjusting refracted and reflected excitation light beams passing through capillaries of a multi-capillary array, to reduce loss of intensity of the laser beams and increase irradiation of respective samples disposed in the capillaries.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims a priority benefit from JapanesePatent Applications Nos. 2001-298987, filed Sep. 28, 2001, and2002-158494, filed May 31, 2002, and claims the benefit of earlier filedU.S. Provisional Patent Application No. ______, filed Sep. 27, 2002 inthe name of Nordman et al., and entitled “Multi-Capillary ArrayElectrophoresis Device” (Attorney Docket No. 5010-055), all of which areherein incorporated in their entireties by reference.

FIELD

[0002] The present application relates to an electrophoresis apparatusfor separating a sample, such as DNA labeled with a fluorescentsubstance, through electrophoresis, and for analyzing the sample.

BACKGROUND

[0003] To determine the DNA base sequence and base length,electrophoresis method using a capillary comprising a fused silica tubeand its polymer covering is utilized. A sample including the DNA to bemeasured is put into the separation medium such as polyacrylamide in thefused silica capillary, and voltage is applied across the capillary.

[0004] The DNA compound in the sample migrates in the capillary and isseparated according to the molecular weight to produce a DNA band in thecapillary. Each DNA band is provided with fluorescence dye, which emitslight in response to laser beam. This is read by the fluorescencemeasuring apparatus to determine the DNA sequence. The same technique isemployed for separation and assaying of a protein to examine theconfiguration.

[0005] According to a laser-irradiated method, a laser beam is directedtoward the capillary on the end of one or both sides of the capillaryarray. The capillary array can consist of multiple capillaries arrangedon a plane substrate. The aforementioned laser beam is transmitted tothe adjacent capillaries one after another across the capillary array.On or around the region of the capillary exposed to laser beam,protective coverings such as polyimide coverings on the surface of thecapillary, can be removed. However, if laser beams pass through theboundary between surfaces having different refractive indices, e.g. thecontact surface between the capillary and air, then the laser light willbe damped by divergence and reflection of the laser light, for example,due to differences in refractive indices of the substances constitutingthe boundary. Consequently, in the process where laser light istransmitted through several capillaries, laser light decaysexponentially, resulting in deterioration of precision in assaying.

SUMMARY

[0006] To reduce loss of the laser beam due to refraction andreflection, a light transfer medium having a predetermined refractiveindex is filled around capillaries. Aspects of techniques that can beadvantageously adapted according to various embodiments include aspectdescribed in U.S. Pat. Nos. 5,790,727; 5,582,705; and 5,833,827; and inJapanese Laid-Open Patent Publication Nos. Hei 09-152418 and 09-96623,all of which are incorporated herein in their entireties by reference.

[0007] According to various embodiments, improvements in assayingprecision of an electrophoresis apparatus are provided wherein a laserbeam can be directed along a beam path to irradiate respectiveirradiatable portions of respective capillaries of a multi-capillaryarray. The improvements include provisions that ensure the simultaneousirradiation of multiple capillaries of the array, for example, thesimultaneous irradiation of all the capillaries of the array.

[0008] Various embodiments provide an electrophoresis apparatus whereinlaser beam is directed along a beam path toward a detection zone thatincludes respective irradiatable portions of the capillaries of thearray. The array contains multiple capillaries that allow a sample to beseparated by electrophoresis. The laser beam is directed along a beampath that ensures the simultaneous irradiation of an irradiatableportion of each capillary of the array, in the detection zone. The laserbeam can pass through multiple capillaries, and fluorescence informationabout the samples migrating through the capillaries can be detected.

[0009] The electrophoresis apparatus can be characterized according tovarious embodiments by including a liquid or solid having a refractiveindex greater than that of air and smaller than that of water, andprovided in the space or region around the capillaries of the array. Theliquid or solid can reduce the amount of the laser beam that isscattered by the capillaries and lost. The liquid or solid can bedisposed around, surrounding, and/or between the capillaries of amulti-capillary array. It is to be understood that the term betweenrefers not only to the area or volume between two capillaries separatedfrom one another, but also to the area or volume between two capillariesthat are in contact with each other.

[0010] According to various embodiments, the configuration can adjustthe refraction and reflection of the laser beam passing throughcapillaries. The adjustment can be used to reduce the loss of lightcaused by passing the light through many capillaries, and can avoid orminimize a reduction in the intensity of light used to illuminate orexcite a sample.

[0011] According to various embodiments, a substance can be disposedaround the capillaries, and can be a liquid, semisolid, or solid at roomtemperature and under standard atmospheric pressure. The refractiveindex of the substance can be lower than that of water. The substance tobe filled around capillaries can have at least the same refractive indexas that of water, or lower. Further, the substance can have a refractiveindex greater than that of air or vacuum, for example, greater than 1.Exemplary substances that can be used for this purpose includefluorine-containing compounds that can be liquid, semi-solid, orpolymeric in form at room temperature and under normal atmosphericpressure. Exemplary substances can have refractive indices of from about1.25 to about 1.32. Other suitable fluorine-containing compounds arediscussed in more detail below.

[0012] Various embodiments provide an electrophoresis apparatus whereinthe aforementioned multiple capillaries can be immersed in a liquid.Such an apparatus can be constructed with one or more feature thataccommodates the expansion of the liquid due to a rise in thetemperature of the liquid, thereby avoiding damage of the vessel orliquid leakage. The temperature of the liquid can be controlled toadjust the gradient of refractive index of the liquid at the site orarea through which the laser beam passes, whereby bending of the laserbeam can be prevented or minimized to preserve the intensity ofexcitation light directed at the sample in each capillary.

[0013] According to various embodiments, an electrophoresis apparatus isprovided wherein a transparent medium having a predetermined refractiveindex is provided around the capillaries, surrounding the capillaries,or between the capillaries of a multi-capillary array. The direction oflight beams emitted from the sample, also referred to herein as emissionbeams, can be adjusted by forming the transparent medium with a curvedsurface. The curved surface can be used to direct emission beams towarda detector and to improve the intensity of emission beams to bedetected.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIGS. 1a and 1 b are a front view and side view, respectively, ofa portion of an electrophoretic apparatus according to variousembodiments, including the irradiatable portions of the capillaries ofthe multi-capillary array of embodiment 1 discussed below;

[0015]FIG. 2 is a schematic external view representing a multi-capillaryelectrophoresis apparatus according to the various embodiments;

[0016]FIGS. 3a and 3 b are schematic views of a detection systemaccording to various embodiments for detecting fluorescent light emittedfrom a multi-capillary array;

[0017]FIGS. 4a and 4 b are, respectively, the image formed on a CCD andobtained from experiment 1 described below, and the distribution of theintensity of emissions from 93 capillaries of a multi-capillary array;

[0018]FIG. 5 shows the result of electrophoresis obtained from theapparatus of embodiment 1 described below;

[0019]FIG. 6a is a front view of a capillary array mounting sectionaccording to embodiment 2 described below;

[0020]FIG. 6b is a cross-sectional view taken along line A-A′ in FIG.6a;

[0021]FIG. 7 shows the result of calculating the temperature gradient online VW;

[0022]FIGS. 8a and 8 b show a side view and front view, respectively, ofa portion of an electrophoretic apparatus according to variousembodiments, including the irradiatable portions of the capillaries ofthe multi-capillary array of embodiment 3 discussed below;

[0023]FIG. 9a is a side view representing a portion of a multi-capillaryarray including the irradiatable portion according to embodiment 4described below;

[0024]FIG. 9b is a side view representing a portion of a multi-capillaryarray including the irradiatable portion according to embodiment 3described below;

[0025]FIG. 10 is a side view representing a portion of a multi-capillaryarray including the irradiatable portion according to embodiment 5described below;

[0026]FIG. 11 is a schematic diagram representing the electrophoreticapparatus of embodiment 6 described below;

[0027]FIG. 12 is a schematic diagram representing the electrophoreticapparatus of embodiment 7 described below;

[0028]FIG. 13 shows the result of simulating the refractive index andemission intensity ratio of a filling medium;

[0029]FIG. 14a shows the image formed on the CCD obtained from theapparatus of embodiment 1 described below;

[0030]FIG. 14b shows the distribution of the intensity of emissions from96 capillaries and corresponds to the CCD image shown in FIG. 14a;

[0031]FIG. 15 shows the result of electrophoresis of one of 96capillaries, according to an embodiment;

[0032]FIGS. 16a and 16 b are schematic drawings representing thelight-gathering lenses of embodiment 8 described below;

[0033]FIGS. 17a and 17 b are schematic drawings representing thelight-gathering lenses of embodiment 9 described below;

[0034]FIG. 18 is a schematic drawing representing the light-gatheringlens of embodiment 10 described below;

[0035]FIG. 19a is a front view of a portion of an electrophoreticapparatus according to various embodiments, including the irradiatableportions of the capillaries of the multi-capillary array of embodiment11 discussed below;

[0036]FIG. 19b is a cross-sectional view taken along line A-A′ in FIG.19a;

[0037]FIG. 20 is a graph showing the relationship between the F polymertransmission wavelength, and transmission percentage;

[0038]FIG. 21 is a table representing the chemical properties of Fsolution;

[0039]FIG. 22 is a drawing representing the refractive index of the Fpolymer;

[0040]FIG. 23a is a front view of an electrophoretic apparatus accordingto various embodiments showing details of a multi-capillary arrayattachment part; and

[0041]FIG. 23b is a cross-sectional view taken along line A-A′ in FIG.23a.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

[0042] [Embodiment 1]

[0043]FIG. 2 is a drawing representing the overall configuration of amulti-capillary electrophoresis apparatus according to variousembodiments. The multi-capillary electrophoresis apparatus can comprisea multi-capillary array 1 consisting of multiple capillaries. Eachcapillary can contain a separation medium for separating a sample to betested. The apparatus can also include a first buffer vessel 11-4 forholding the buffer 3 such that a negative electrode 2 of themulti-capillary array, and a sample introduction part 11-3, can beimmersed. The apparatus can include a gel block comprising a valve 6,and a second buffer 11-7 for holding the buffer 12 and wherein the gelblock 4 and a ground electrode 7 can be immersed. The apparatus caninclude: a syringe 10 for supplying a gel as a medium forelectrophoresis in the capillary array; a measuring part 11-8 forobtaining information on the sample; a light source 11-1 for applying alight source such as a laser beam 9 as a coherent light to theirradiatable portions of the capillaries; a measuring part (notillustrated) for measuring fluorescent light emitted from the respectivesamples; an oven with air-circulation 11 for adjusting the temperatureof capillary array; and a high voltage power source 11-2 for applyingvoltage to the separation medium.

[0044] The multi-capillary array 1 can contain 96 fused silicacapillaries as tubular members filled with aqueous polymer solution as aseparation medium for separating fragments of a DNA molecule in a sampleto be tested. A sample introduction part 11-3 can be provided forintroducing the sample into the capillary. The part 11-3 can be formedon one end of the multi-capillary array 1 where an electrode 2 forapplying negative voltage can be arranged. On the other end of the arraya connection part 5 can be provided connected with the gel block 4 toallow injection of the separation medium from the gel block 4 to themulti-capillary array 1.

[0045] The measuring part 11-8 including the irradiatable portions 8that are to be exposed to excitation light can be located between thesample introduction part 11-3 and connection part 5.

[0046] The gel block 4 and syringe 10 form a fluid medium injection part11-5 for injecting aqueous polymer solution as a separation medium intothe capillary. When the aqueous polymer solution as a separation mediumis injected into the capillary, the valve 6 can be closed and thesyringe 10 can be inserted into position, whereby the aqueous polymersolution can be injected into the capillary. The multi-capillary array1, gel block 4, buffer 3, electrode 2, buffer 12, ground electrode 7 andhigh voltage power source 11-2 constitute a voltage application part forelectrophoresing the sample under test. At the time of electrophoresis,the negative electrode 2 can be immersed in the buffer 3 and the valve 6can be opened. This establishes a conducting path consisting of thenegative electrode 2, buffer 3, multi-capillary array 1 including theaqueous polymer solutions in the capillaries, gel block 4 includingaqueous polymer solution in the gel block, buffer 12, and groundelectrode 7. Voltage can be supplied to this conducting path from thehigh voltage power source 11-2. When voltage is applied to theconducting path, the sample under test in aqueous polymer solutionstarts to migrate and is separated in conformity to the properties suchas molecular weight.

[0047] The air-circulating oven 11 is a temperature control part forcontrolling the temperature of the capillary array. This allows thegreater part of the capillary array 1 to be kept at a constanttemperature (e.g. at 60° C.).

[0048] The optical system of the electrophoresis apparatus comprises thelight source 11-1, the measuring part 11-8 containing the irradiatableregion 8, and the measuring or detecting part for detecting thefluorescent light emitted from the irradiatable portions of thecapillaries. The light source 11-1 can generate a laser beam 9 (488.0 nmand 514.5 nm beams emitted from an argon ion laser) as coherent light.

[0049] The excitation light laser beam 9 is directed toward theirradiatable region 8. The capillaries of the array can be arrangedparallel and adjacent to one another in a plane in the measuring part11-8. Excitation light such as laser beam 9 can be applied to ordirected at the measuring part 11-8 from two directions—upward anddownward directions—in order to ensure simultaneous excitation throughirradiation parts 8 of multiple capillaries. The excitation light laserbeam 9 can excite a sample being tested, to cause fluorescent light tobe emitted from the sample. Various embodiments provide informationabout the sample, such as a nucleic acid base sequence.

[0050]FIG. 3a shows a detection mechanism 34-2 and measuring part 8. Thedetection mechanism 34-2 can comprise or can consist of a fluorescentlight collimating lens 31, a grating 32, a focus lens 33, and a CCD 34.Fluorescent light 35 emitted from samples contained in the respectivecapillaries and irradiated with excitation light, is converted intoparallel beams or rays of light by the fluorescent light collimatinglens 31. The collimated light is then split spatially by the grating 32and an image is formed on the CCD 34 by the focuing lens 33. Optics forimage formation are depicted in the FIG. 3b schematically. Ninety-sixcapillary images are arranged in the Y-axis direction, and light emittedfrom each capillary is dispersed in the X-axis direction.

[0051] The following describes the measuring part 11-8: FIG. 1 containsa side view (1 a) and front view (1 b) of the measuring part 11-8. Themeasuring part 11-8 consists of 96 capillaries 16, array base 15, cellcover 20, holding plate 17, bubble eliminating block 23, filled medium(F solution 19) and bubble 22.

[0052] The following describes the capillary array structure: Areference plane surface for placing the capillary is formed on the arraybase 15. To ensure that all 96 capillaries are kept in contact with thereference plane surface and adjacent capillaries are kept in contactwith each other, they are arranged on the array base 15.

[0053] The capillaries 1 can be bonded to the array base 15 and arefixed in position by being inserted between the holding plate 17 forfixing the capillaries 1 and the array base 15. This allows thecapillaries to be arranged in parallel on the plane surface, and thevariation in the distance of the center axis of each capillary from theplane surface is kept at 6 μm or smaller. Consequently, this will reducethe influence due to the loss of laser beam 9 resulting from diffusionand reflection when laser beam 9 is irradiated so as to propagatesuccessively to the adjacent capillary across 96 capillaries.

[0054] The following describes the capillary configuration: Eachcapillary 16 can be configured in such a way that the fused silica tube18 can have, for example, an inner diameter of about 50 μm and an outerdiameter of 126 μm that can be covered with a 12-μm thick polymercoating. The overall outer diameter can measure, for example, 150 μm.The capillary can be filled with aqueous polymer solution (having arefractive index of about 1.41, for example) as a DNA separation medium.

[0055] In the region of each capillary tube that includes a lightirradiatable part 8, also referred to herein as an irradiatable portion,to which excitation light is directed, the polymer coating can beremoved to expose the underlying fused silica 18 of the capillary. Whenexcitation light, for example, laser beams 9, are directed to theirradiatable parts 8, part of the irregularly reflected light contactsthe polymer coating of the capillary and the polymer coating can emitfluorescent light in some cases. However, the fluorescent light fromthis polymer coating can be blocked by the holding plate 17, andprevented from reaching the detection mechanism. This ensures highsensitivity detection characterized by a high signal to noise ratio.

[0056] According to various embodiments, a sealed structure can beformed by the array base 15 and a fused silica-made cell cover 20 bybonding together with an adhesive 21, thereby providing a sealed cellfor holding a transparent medium such as specific liquid and/or solid.Filling this cell with transparent medium ensures that the space throughwhich excitation light passes between the capillaries is filled with thetransparent medium. In other words, the irradiatable parts 8 of thecapillaries 1 can be immersed in the transparent medium. Since the highvoltage is applied to the capillary during electrophoresis, thecapillary attracts the dust particles in charged air. However, since theportions of the capillaries including the irradiatable portions areseparated from the outside by the sealed cell, the irradiatable parts 8do not attract and hold dust particles.

[0057] Selection of the aforementioned transparent medium has a seriousimpact on the analysis capability in the assaying of electrophoresis. Toexplain this, the following describes the problems with the propagationand loss of laser beam. According to various embodiments, laser beams 24and 25 are directed so that they will overlap with each other. Each oflaser beams propagates successively to the adjacent capillaries oneafter another, across 96 capillaries to traverse the irradiation part 8of the capillary. Here when the laser beams 24 and 25 travel across theboundary between the capillaries 16 and the transparent medium, laserbeams 24 and 25 have to pass through the boundary between the mediahaving different refractive indices, with the result that lightintensity will be lost due to scattering of the laser beam caused byrefraction and reflection. When light intensity of laser beams 24 and 25is weakened by this loss, fluorescent light emitted from samples in thecapillaries 16 will be reduced, so highly sensitive analysis of DNAsequence and others will be difficult to achieve.

[0058] To solve the problem of the loss of laser beams, fluorescentlight can be increased by raising the laser beam intensity. However, ifthe intensity of the laser beam is excessive, the test sample such as aDNA molecule or the like will be denatured. In this sense, this methodis restrictive. Further, in an electrophoresis apparatus where a laserbeam passes through multiple capillaries, a problem is found in thedifference of the intensities of laser beams reaching and irradiatingeach of the different capillaries. As the laser beam passes through thecapillaries, the intensity is decreased exponentially due to refractionand reflection. A large difference occurs between the fluorescent lightemitted from the capillary where the incoming laser beam intensity isthe strongest and that from the capillary that is the weakest (thecapillaries located at the center when laser beams are used toirradiated a multi-capillary array from both sides). In this case, thedetection range of the CCD 34 must be set in such a way that all thefluorescent light can be accommodated. So if there is a large differencein the intensity of fluorescent light, the analysis performance of theCCD 34 cannot be effectively utilized, with the result that analysisperformance will be deteriorated. For this reason, if there is a largedifference in the intensity of laser beams from one capillary toanother, the samples in the capillaries cannot be analyzed effectively.The loss due to retraction and reflection is increased exponentially asthe number of capillaries in which laser beam propagates is increased.In an electrophoresis apparatus comprising about 24 or more capillaries,a significant problem can be the loss in the intensity of excitationlight due to refraction and reflection. Loss caused by refraction andthat caused by reflection depend on the difference in the refractiveindex on the boundary. If there is a significant difference in therefractive indices of the two sides of the boundary, (if the reflectionfactor is significant), attenuation can be caused by reflection when theexcitation light passes through the boundary. If the difference in therefractive indices is small, attenuation can be caused by divergence ofthe excitation light, or laser beams, when the light passes through theboundary. To solve this problem according to various embodiments, thepresent inventors have found out it is effective to reduce the totalloss due to refraction and reflection by filling the space betweencapillaries with a medium having a predetermined refractive index.

[0059] The following describes the loss due to reflection: The followingformula is generally used to obtain the reflection factor (R) when lightpropagates at an incident angle of 0 from medium 1 (refractive rate: n1)to medium 2 (refractive index: n2):

Reflectance: R={(n1−n2)/(n1+n2)}²

[0060] For example, when air is used to fill around the capillaries,reflection factor on the boundary between air (n=1.00) and fused silica(n=1.46) is 3.49%. So every time laser beam passes through one boundary,beam of 3.49% is reflected, with the result that light intensity will belost. This loss is increased exponentially with the increase in thenumber of capillaries passed by laser beam. To reduce the loss caused byreflection, the refractive index of the filling medium should be madecloser to that of the capillary.

[0061] Further, the loss caused by refraction is the attenuationresulting from diffusion of laser beam passing through the boundary. Inother words, when the capillary has a cross section shaped in an ellipseor a circle, the boundary between the capillary and filling medium willact as a converging lens

[0062] Because the index of refraction of the separation medium (n=1.41)is less than that of the fused silica capillaries (n=1.46), the lumen ofthe capillary will act as a diverging lens. The capillary inner diameteris smaller than the capillary outer diameter so the diverging lenseffect is for the same index of refraction difference.

[0063] If the capillary and its medium have a small refractive indexdifference, the lens effect of the boundary will be reduced, and thelaser beam is diverged to cause loss. Generally, the following formulais used to obtain the relationship between incoming angle è1 andoutgoing angle è2 when light has launched from medium 1 (refractiverate: n1) to medium 2 (refractive index: n2):

n1 sin è1=n2 sin è2

[0064] For this reason, to increase the lens effect of the capillary andto reduce the loss due to refraction, it is generally necessary toincrease the difference in refractive index between the filling mediumand capillary. Based on this way of thinking, various embodimentsinvolve using a simulated relationship between the refractive index N ofthe transparent medium around the capillary, and emission intensityratio. This simulation was made using a multi-capillary array having 96capillaries equipped with the same structure of the irradiatable part asthat of the present embodiment, wherein the capillary was filled withaqueous polymer solution having a refractive index of 1.41, and laserbeams were directed at both sides of the capillary array. The variationin distance from capillary center axis to the plane surface was ±6 μm,and the laser diameter was 72 μm, with the misalignment of optical axisassumed at 10 μm.

[0065]FIG. 13 shows the result of this simulation. The horizontal axisindicates the refractive index of the transparent medium, and thevertical axis shows the intensity of laser beam which passes through theinside of each capillary averaged for 96 capillaries relative to theintensity of incident laser beam. The intensity had a serious impact onthe analysis performance of the CCD as means for detecting fluorescenceof the test sample. The boxes in the middle of the vertical lines on thegraph indicate the expected values of the emission intensity ratio. Thelines in the vertical direction including the boxes show thedistribution of the emission intensity. It can be seen that the emissionintensity ratio is shaped like a cone whose apex is formed by therefractive index of about 1.29, with respect to the refractive index ofthe filling medium. When the refractive index is smaller than 1.29, theloss caused by reflection is greater. When refractive index is 20 largerthan 1.29, the loss caused by refraction is greater. If the emissionintensity ratio is 0.35 or greater, it can be seen that the transparentmedium around the capillaries is preferred to have a refractive indexfrom 1.25 to 1.32. The transparent medium having a refractive index of1.29 can be used.

[0066] A transparent medium can be selected that does not absorbexcitation light, for example, laser beams. This is to reduce theattenuation of light intensity when laser beam passes through thetransparent medium. This attenuation will increase if there are agreater number of capillaries and the laser beam path in the transparentmedium is longer. Further, a transparent medium can be selected thatdoes not emit fluorescent light. If the transparent medium emitsfluorescent light due to exposure to the excitation light, thefluorescent light will create noise and create background which reducesthe dynamic range with the result that the performance of the analysiswill be deteriorated.

[0067] According to various embodiments, the transparent medium can beFluorinert Electronic Liquid FC-43 (hereinafter abbreviated as “Fsolution 19”), where “Fluorinert” is a registered trademark of 3M, Inc.

[0068] The F solution 19 is a fluorinated liquid having a refractiveindex of about 1.29, and a low viscosity. It is colorless, transparent,and very stable in thermochemical properties. It does not absorb laserbeams. Even when exposed to laser beams, it emits fluorescent lighthaving an intensity equivalent to, or less than, the Raman scattering ofwater. Accordingly, this provides a very suitable material for themedium of a multi-capillary array electrophoresis apparatus. Further, ithas the following characteristics, which are included in transparentmedium according to various embodiments (1) excellent electricinsulation and thermal conductivity, (2) very small surface tension andsuperb permeability, (3) insolubility in solvents whether temperature ishigh or low, (4) non-combustibility and free of poison and odor, and (5)an inactivity without corroding electronic parts, metal, plastic, orrubber.

[0069]FIG. 21 shows the chemical properties of F solution at 25° C. Thesealed vessel of the multi-capillary array in the present embodiment isfilled with F solution 19, and the irradiation part 8 is immersed in Fsolvent 19. This reduces the loss of intensity of the laser beams whenthey pass through the surface of the capillaries 16, and avoidsreduction of the intensity of fluorescent light emitted from the testsample. These characteristics ensure improved analysis performance in amulticapillary array electrophoresis apparatus having multiplecapillaries, for example, having 24 or more capillaries. The sealedstructure can be is filled with a bubble 22 as well as with F solution19. This is to prevent the closed structure from being damaged by theexpansion of the volume of F solution 19 resulting from temperaturechange. However, since the bubble 22 is made movable, it may immigrateinto the laser light path to give an adverse effect to analysis. Toprevent the bubble 22 from crossing the laser light path, a fusedsilica-made bubble-eliminating block 23 as a bubble eliminator can beformed in the sealed structure.

[0070] The bubble-eliminating block 23 can be in an upper position whenthe measuring part 11-8 is mounted on the electrophoresis apparatus. Itis placed in the path of the laser beams 24 and 25. Then the space 20-2for storing bubble 22 can be formed above the sealed vessel where laserbeams 24 and 25 do not pass. At the time of measurement, bubble moves tothe upper portion of the cell, and remains in this space 20-2, therebypreventing the bubble 22 from crossing the laser beam paths.

[0071] Further, when the irradiation part 8 is mounted on theelectrophoresis apparatus so that the reference surface of the arraybase 15 is horizontal and capillaries are located lower than thereference surface, a groove-formed space is formed on the array base 15close to the irradiatable part 8. The bubble tends to stay in the gap ofcapillaries close to the irradiation part. However, if the volume in thegroove-formed space is equal to or greater than that of the bubble 23,then the bubble remains in this space, with the result that contactbetween the bubble 22 and laser beams 24 and 25 can be avoided.

[0072] Further, the same effect can be obtained when the irradiationpart 8 is mounted oblique to the electrophoresis apparatus in such a waythat the bubble 22 moves to one end of the sealed vessel where it is notexposed to the laser beams 24 and 25. In other words, when theirradiation part is mounted on the electrophoresis apparatus, the sealedstructure is configured so that the staying bubble is not exposed tolaser beams 24 and 25, whereby contact between the bubble 22 and laserbeams 24 and 25 can be avoided. This configuration avoids the loss dueto refraction and reflection caused by laser beams passing by theboundary between the bubble and F solution 19.

[0073]FIGS. 14a and 14 b show the image formed on the CCD according toan embodiment and the distribution of the intensities of emissions from96 capillaries. FIG. 4 shows the image formed on the CCD for 93capillaries and the distribution of the intensities of emissions from 93capillaries. The emissions shown in FIGS. 14a and 14 b represent aspectrum (mainly the Raman scattering of water) emitted from theseparation medium. As illustrated, emission from 96 capillaries can bedetected at the same time.

[0074]FIG. 15 shows the result of electrophoresis of one of 96capillaries. FIG. 5 shows the result of electrophoresis of one of 93capillaries. The current target of measurement is the DNA sample(so-called size maker) with its base length known. The temperature inthe air-circulating oven is 60° C., and the length between theirradiation part and sample introduction terminal is 36 cm, with theaverage field applied to the capillary being 319 volts per centimeter. Acrossover point is one of the indices for indicating the DNAseparability of the electrophoresis. This means the length of a basewhere the separation length equivalent to one base on the irradiationpart is equal to the full width at half maximum of the DNA band of onebase. It shows that the greater this value, the greater the separabilityin electrophoresis. The crossover point in FIG. 15 has been found in 410bases. The same result has been gained from other 95 capillaries. Thecrossover point in FIG. 5 has been found in 410 bases. The same resulthas been gained from other 92 capillaries.

[0075] As described above, various embodiments provide a multi-capillaryelectrophoresis apparatus of high analysis performance where thecrossover point for each capacity is found in 410 bases.

[0076] [Embodiment 2]

[0077] The angle formed between an incoming laser beam and laser entrysurface on a multi-capillary array, or cell, can be maintained constant.If this angle is different for each capillary array, the incident angleof the laser will vary, with the result that the laser light path in thecell will vary. For example, if the laser entry surface on the cell ismade of fused silica, and the medium filling the cell is a liquid havinga refractive index of 1.29, the displacement of the laser light path atthe point where the laser beam has propagated in 20 mm from the entrypoint into the cell will be 20 μm if the laser entry surface of the cellvaries by 4 mrad.

[0078] If laser is displaced in the axial direction of the capillary,two laser beams irradiated in two directions (upward and downwarddirections) can cease to be coaxial, and the effective laser diametercan be increased, with the result that performances such as separabilityin DNA detection will be deteriorated. Further, if laser beam isdisplaced in the direction (hereinafter abbreviated as “Z-axisdirection”) vertical to both the capillary axis and the laser beam axis,the amount of laser beam irradiation of the inner diameter of thecapillary will be reduced, and the signal intensity will decline. Toavoid such deterioration in performance, it is necessary to ensure thatthe angle formed between incoming laser beam and laser entry surface onthe cell is maintained constant.

[0079] In a multi-capillary array electrophoresis apparatus according tovarious embodiments, the inner diameter of the capillary filled with aseparation medium and test sample is 50 μm, the tolerance of thedistance of center axis of the capillary and the reference surface is ±6μm, and the excitation light is a laser light having a diametermeasuring 72 μm that can be precisely adjusted to the order of μm.Otherwise, the satisfactory sensitivity cannot be maintained. Further,the multi-capillary array can be dismountable from the electrophoresisapparatus.

[0080] When it is to be mounted, a precise and easy positioningadjustment between the capillary and laser beam can be provided. Forthis reason, the embodiment 2 can be configured in such a way that aconstant angle maintained between the reference surface for mounting themulti-capillary array on the electrophoresis apparatus and the laserentry surface on the cell, and a constant angle can be maintainedbetween this reference surface for mounting and that on the apparatusside at all times. The surface where multiple capillaries are arrangedcan be brought in contact with the mounting reference surface on themulti-capillary array mounting section of the electrophoresis apparatus,whereby adjustment can be made of the relative position between theplane substrate and the electrophoresis apparatus in the directionvertical to the aforementioned mounting reference surface. At the sametime, the one plane surface in the cell which is vertical to the planesurface where capillaries are arranged and parallel to the axes of thecapillaries, can be brought into contact with another mounting referencesurface on the multi-capillary array mounting-section. An adjustment canthus be made of the relative position between the capillary array andthe electrophoresis apparatus in the direction vertical to theaforementioned vertical direction. As such, a constant angle can bemaintained between the incoming laser beam and laser entry surface ofthe cell.

[0081]FIG. 6 shows the front view (6 a) of the capillary array mountingsection according to the embodiment 2 25 and a cross-sectional viewtaken along line A-A′ of the front view shown in FIG. 6b. Othersarrangements can include the same as those described in Embodiment 1above. The X, Y and Z axes are defined as shown in the figure. TheX-axis is the axis parallel to the capillary axis, and Z-axis is theaxis vertical to the reference plane surface where multiple capillariesare arranged, with the Y-axis being the axis vertical to both the X- andZ-axes.

[0082] On the fused silica-made array base 15 are formed a referenceplane surface 40-2 where the capillaries can be arranged through contactwith the polymer coating of the capillaries, a mounting referencesurface 40 in contact with the electrophoresis apparatus and a mountingreference surface 46. The mounting reference surface 46 of the arraybase 15 is vertical to the reference plane surface 40 and is parallel tothe Xaxis.

[0083] The reference plane surface 40-2 is approximately parallel to themounting reference surface 40, and the distance between them ispreferred to be 6 μm or smaller. If the reference plane surface 40-2 andmounting reference surface 40 are formed on one and same plane as in thepresent embodiment, the capillary array can be produced to a highprecision, so this formation is preferable.

[0084] On the capillary mounting section on the electrophoresisapparatus is formed a mounting reference surface 41 and mountingreference lines 47 and 48 to which the mounting reference surface 40 ofthe multi-capillary array and the mounting reference surface 46 arerespectively brought in contact. It contains a laser beam transmissionpart 51-7 passed by the laser beams 24 and 25 entering the irradiatablepart 8, a fluorescent light transmission part 51-6 passed by thefluorescent light emitted from the sample, a pressure part 51-8comprising a mounting section cover 51-11 and spring 51-10, and apressure part 51-9 comprising a holding rod 44 and spring 45. Thepressure part 51-8 can be moved when the multi-capillary array ismounted or dismounted from the capillary array base. When it is mounted,the mounting reference surface 40 is brought in contact with themounting reference surface 41 of the multi-capillary array mountingsection of the electrophoresis apparatus. The array base 15 is pressedin the −z axis direction (from the mounting reference surface 40 tomounting reference surface 41) by pressure part 51-8, whereby therelative positioning between the array base 15 and electrophoresisapparatus in the Z-axis direction can be carried out with a high degreeof precision on the order of μm. This positioning ensures thereproducibility of the positions for the laser beams and theirradiatable portions when the capillary is mounted. When the referenceplane surface 40-2 and the mounting reference surface 40 are located onthe same plane, positional relationship between the center axis of eachcapillary and the path of laser beams 24 and 25 can be adjusted with anextremely high degree of precision.

[0085] When the mounting reference surface 46 of the array base 15 isbrought in contact with two capillary mounting reference memberssemicircular as viewed from above the Z-axis, it is brought in contactwith the mounting reference lines 47 and 48. The array base 15 ispressed against it in the Y-axis direction (from the mounting referencesurface 46 to the mounting reference lines 47 and 48) by the spring 45through the holding rod 44 comprising two capillary holding memberssemi-circular as viewed from above the Z axis. As described above, onestraight line is in contact at two points as viewed from the Z-axisdirection, and this enables relative positioning between the array base15 and the electrophoresis apparatus in the Y-axis direction with a highdegree of precision.

[0086] In the capillary array, capillaries are arranged so that themounting reference surface 46 and each capillary will be parallel witheach other. Further, the distance between the capillary 49 closest tothe mounting reference surface 46 and the mounting reference surface 46is made constant for any capillary array. This allows the positionrelationship between each capillary and the mounting reference lines 47and 48 to be determined uniquely for the capillaries ranging from theclosest capillary to all the following 95 capillaries. Accordingly, theposition of imaging on the CCD 34 does not depend on the capillaryarray, and the light receiving surface of the CCD 34 can be minimized.

[0087] If the laser light path varies in the X-axis direction, the laserbeams 24 and 25 in the two upper and lower directions ceases to becoaxial, so the laser beam diameter increases effectively. This willresult in the reduction in performances such as reduction in theseparability for DNA detection. If the laser beams 24 and 25 aredisplaced in the Z-axis direction, there will be a reduction in theamount of laser beam irradiated inside the capillary, with the resultthat signal intensity is reduced. To avoid reduction in performances,surfaces 50, 51, 52 and 53 are made parallel to the surface 46, asdescribed above. To minimize the variations of the laser light path, theangle of mounting the array base 15 on the electrophoresis apparatusshould be made constant with a high degree of reproducibility. Thiscondition can be met according to the aforementioned method of pressingthe surface 46 against the lines 47 and 48.

[0088] The following describes various embodiments for mounting amulti-capillary array on a capillary array mounting section. FIG. 23shows the front view (23 a) of the capillary array mounting section asan variation of the embodiment 2 and cross sectional view taken alongline A-A′ in the front view of FIG. 23b. The X, Y and Z axes are definedas shown in the figure. The surface 40 of the array base 15 (surface incontact with the capillary polymer coating) is brought in contact withthe mounting reference surface 41 on the array mounting section of theelectrophoresis apparatus, thereby adjusting the relative positionbetween the array base 15 and the electrophoresis apparatus in theZ-axis direction. This position adjustment has ensured thereproducibility of the position exposed to laser beam when the capillaryarray is mounted or remounted. Further, the array base 15 is pressed inthe Yaxis direction by the spring 45 through the holding rod 44, and thesurface 53 of the cell (vertical to the surface 40 and parallel to the Xaxis) is brought in contact with the mounting reference lines 47 and 48,thereby adjusting the relative position between the array base 15 in theY-axis direction and the electrophoresis apparatus. Further, thecapillaries of the capillary array are arranged so that the surface 53is parallel to each capillary, and the distance between the capillary 49closest to the surface 53 and the surface 53 is made constant for anyone of the capillary arrays. As a result, the position of imaging on theCCD 34 does not depend on the capillary array, and the light receivingsurface of the CCD 34 can be minimized.

[0089] All the capillaries can be aligned in a specific area of thearray base, parallel to the reference surface 46. The largest andsmallest distances of the edge of the specific area are predeterminedfor any capillary array. This structure is realized in such a way asdescribed with reference to FIG. 8 where two parallel blocks are formedon the array base, and the area between the blocks are the specific areawhere 96 capillaries are aligned. In this case, it is necessary to keepconstant the distances of inner wall (capillary-side wall) of the twoblocks and reference surface 46 for any capillary arrays. The lightreceiving surface of the CCD 34 can be minimized with thisconfiguration.

[0090] The parallelism of the surfaces 50, 51 and 52 exposed to thelaser beams 24 and 25, and surface 53, out of the surfaces of the fusedsilica-made cell cover 20, is made to be 2×10⁻³ rad or smaller. If thisparallelism varies for each capillary array, the incident angle of thelaser beams 24 and 25 upon the cell 20, hence, the laser light path inthe cell varies. If the laser light path varies in the X-axis direction,the laser beams 24 and 25 in the two upper and lower directions cease tobe coaxial, so the laser beam diameter increases effectively.

[0091] This will result in the reduction in performances such asreduction in the separability for DNA detection. If the laser beams 24and 25 are displaced in the Z-axis direction, there will be a reductionin the amount of laser beam irradiated inside the capillary, with theresult that signal intensity is reduced. To avoid reduction inperformances, surfaces 50, 51 and 52 are made parallel to the surface53, as described above.

[0092] To minimize the variations of the laser light path, it is notsufficient to ensure that the surfaces 50, 51 and 52 are parallel to thesurface 53. It is also necessary to ensure that the angle of mountingthe array base 15 on the electrophoresis apparatus is constant with ahigh degree of reproducibility. This condition can be met according tothe aforementioned method of pressing the surface 53 against the lines47 and 48.

[0093] In the method shown in FIG. 6, the cell 20 can be installed andbonded to array base 15 in such a way that the surface 50 of the cell 20and the surface 46 of the array base 15 will be parallel to each other.According to this method, the surface 53 of the cell 20 can be broughtin direct contact with the mount reference lines 47 and 48, resulting anincreased margin of parallelism between the array base 15 and cell 20.

[0094] According to various embodiments, the resolution of theelectrophoresis apparatus deteriorates if temperature gradient occurs tothe filling medium between capillaries, and this is caused by thebending of laser beam due to gradient of the refractive index in thefiller medium. According to various embodiments, a solution to problemis provided. If there is a temperature increase of the medium (Fsolution 19) in the Z-axis direction, the refractive index of the Fsolution 19 will increase in the Z-axis direction. This increase ofrefractive index causes the propagating direction of the laser beams 24and 25 ideally having only the components the Y-axis direction will cometo have components in the Z-axis direction although in a small amount.The direction of laser beams 24 and 25 propagating in the Y-axisdirection will be displaced in the Z-axis direction by the gradient ofthis refractive index, causing the laser beam to deviate from thecapillary array. This reduces the intensity of the laser beams appliedto the capillary, hence the signal intensity (intensity of thefluorescent light emitted from the samples), resulting in a deterioratedsensitivity of the electrophoresis apparatus. This problem is moreconspicuous with the increase in the distance of the laser beams 24 and25 passing through the medium (increase in the number of capillaries).The problem can be solved by adjusting the surface temperature insidethe sealed vessel, without having to use a complicated configuration.Based on this assumption, various embodiments examine the relationshipbetween difference in the internal surface temperature and the gradientof the temperature at a preetermined position in the filling medium. Theresult is given in FIG. 7.

[0095]FIG. 7 shows the temperature difference between point 54 and point55 in the array shown in FIG. 6, with the gradient of the temperature ona straight line between points 54 and 55. The horizontal axis indicatesthe Z-axis coordinate on the line between points 54 and 55, and Z=0 axisis equivalent to the center position of the capillary.

[0096] The line between points 54 and 55 is vertical to the array base,and passes through the center of the space between capillaries. Thedistance between points 54 and 55, i.e., thickness of the F solutionlayer, is 0.8 mm, and the vertical axis indicates the temperaturegradient. T denotes the difference in temperature between point 54 andpoint 55 (where .T=temperature at point 54−temperature at point 55).Each curve represents the temperature gradient on line 54-55 for the Fsolution when .T is −20, −5K, −2K, 2K, 5K and 20K. The thermalconductivity of F solution is 0.066 W/mK, and the specific heat is 1050J/kgK, with the density at 1880 kg/m3. Further, for calculation, heatgeneration for each capillary during electrophoresis is assumed to be 1mW per 10 mm in length.

[0097] As can be seen from FIG. 7, the absolute value of temperaturegradient is smaller when .T is positive (temperature at point 54 isgreater than that at point 55) than when it is negative. In other words,the deviation of the temperature gradient is smaller when thetemperature of the plane substrate of the array base 15 is higher thanthat of the cell cover 20, than the reverse case. Based on this result,the multi-capillary array has been designed as shown in FIG. 6. Themulticapillary array according to the present embodiment is configuredin such a way that the thickness of the fused silica-made array base 15as a first flat plate of the sealed vessel is larger than that of thefused silica-made cell cover 20 (the thickness of the transparent plateas part of the aforementioned cell passed by the signal light from thecapillary array to be detected) as a second flat plate. If the arraybase 15 is made of sapphire, the .T can be kept positive even if thearray base 15 is thinner than the cell cover. In other words, thecapillary array is designed in such a way that the thermal conductionefficiency of the first flat plate is greater than that of the secondflat plate.

[0098] In this manner, when the multi-capillary array mounting sectionis kept at a constant temperature of e.g. 60° C., the array base 15transmits the heat to the surfaces 40 and 41 (mounting reference surface40 and mounting reference surface 41) more effectively than the cellcover portion in contact with the surfaces 47 and 48. Themulti-capillary array mounting section can be kept at a constanttemperature of, for example, 60° C., whereby .T is maintained positive.This will reduce the temperature gradient, hence refractive indexgradient. This ensures straight traveling property, and improvesresistance of the laser light path against bending. The multi-capillaryarray can be designed so that temperature gradient of the filling mediumat the site passed by laser beam will be zero during electrophoresis.The temperature gradient being zero signifies that laser beam can travelstraight because there is almost no temperature gradient, andsensitivity is hardly deteriorated by bending of laser beam.

[0099] The aforementioned configuration improves the resolution of anelectrophoresis apparatus where the space between capillaries is filledwith the filling medium.

[0100] [Embodiment 3]

[0101] The embodiment 3 characterized in that the medium uses Teflon AF2400 of Dupont (hereinafter abbreviated as “F polymer”) as a fluorinatedpolymer having a refractive index of 1.29 or Teflon AF 1600 of Dupont(hereinafter abbreviated as “F′ polymer”) as a fluorinated polymerhaving a refractive index of 1.32. Here “Teflon” is a registeredtrademark of the Dupont product.

[0102]FIGS. 8a and 8 b show a side view (8 a) and front view (8 b) of aportion of the apparatus of embodiment 3 including the irradiatableportions of the capillaries. Configurations other than the irradiatablepart 8 are the same as that of embodiment 1. Further, it is alsopossible to use the medium containing the recurring unit that has atleast one of the following chemical structures A, B, C and D. They arecharacterized in that all the hydrogen atoms have been replaced byfluorine atoms. Similarly to the aforementioned F solution, they can beused as excellent transparent mediums.

[0103] The irradiation parts 8 of the capillary array 1 are formed onthe array base 15. They are arranged on the array base 15 and are bondedand fixed to the array base 15 together with the holding plate 17 inorder to ensure that the capillaries on the array base 15 will contactthe array base 15 and the adjacent capillaries. This configurationuniquely determines the positional relationship between each capillaryand mounting reference surface, similarly to embodiment 2.

[0104] The capillaries 16 can be covered with a thin polymer film,similarly to the case in embodiment 2. In the irradiatable part 60-2,the polymer coating is removed and the fused silica tube 18 is exposedto the outside. In the invention according to the embodiment 3, theirradiatable part 60-2 where the fused silica tube 18 is exposed to theoutside is covered with the F polymer as a fluorinated polymer having arefractive index of 1.29. It can also be covered by Teflon AF 1600 ofDupont (a registered trade mark) (hereinafter abbreviated as “F′polymer”) as a fluorinated polymer having a refractive index of 1.32.

[0105] After the capillary 16 has been fixed to the array base 15, thespace between capillaries is filled with F polymer 60. The polymer 60has been filled in such a way that the laser light paths 24 and 25 arecompletely covered in the space between two polymer blocks 61 and 62located at the outer positions on both ends. The following shows achemical formula E for the F polymer, where “n” is a natural number.

[0106] Further, the F polymer and F′ polymer are characterized asfollows: (1) High temperature stability, (2) Excellent chemicalresistance, (3) Low surface energy, (4) Low water absorption, (5)Transparency and superb light transmission, (6) Very low refractiveindex, and (7) high gas permeability.

[0107]FIG. 20 is a graph showing the F polymer transmission spectrum.From this drawing, it is apparent that the F polymer 60 is suited foruse as a filling medium since it does not absorb the fluorescent lightof the argon laser having a wavelength of 488.0 nm and 514.5 nm, and itdoes not emit fluorescent light even if this light is irradiated.

[0108]FIG. 22 shows the refractive index of the F polymer and F′polymer. The refractive index of F polymer at a temperature of 20° C.according to sodium D ray is 1.29, and that of F′ polymer at atemperature of 20° C. according to sodium D ray is 1.32.

[0109] The refractive index has been measured by an ABB reflectionmeasuring instrument using alpha-bromonaphthalene as a contact liquid.This refractive index is known to be the lowest value for the solidorganic polymer. The refractive index of the AF2400 is close to thetheoretical minimum critical value of the solid organic polymerrefractive index expounded by Groh and Zimmerm.

[0110] As described above, when the space between capillaries is filledwith the fluorine containing polymer having a refractive index from 1.25to 1.32, for example, 1.29, it is possible to avoid loss of lightintensity due to the refraction and reflection caused when laser beams24 and 25 pass through the surface of the fused silica tube 18. Almostthe same signal as that of embodiment 1 can be obtained.

[0111] [Embodiment 4]

[0112]FIG. 9a is a side view representing the portion close to thelaser-irradiation part according to an embodiment 4. In this embodiment,the surface of the filled F polymer 60 is configured in such a way thatthe cross section forms a circle concentric with the capillary 16, asshown in FIG. 9a. Otherwise, the configuration is the same as that ofembodiment 3.

[0113] In embodiment 4, the fluorescent light collimating lens 31 isassumed to have an F value of 1.8. When the surface of the F polymer 60has a plane surface (FIG. 9b), the signal is refracted by the boundary65 between air and F polymer 60.

[0114] Accordingly, only the signal light within ±12° in the capillarycross section can reach the fluorescent light collimating lens 31, asillustrated. In the meantime, if the surface of the F polymer 60 isdesigned as a circle concentric as that of the capillaries 16, then thesignal light within ±15.5° in the capillary cross section can reach thefluorescent light-collimating lens 31. When fluorescent light emittedfrom the test sample in the capillary passes through the boundarybetween the fused silica tube and F polymer 60, and the boundary betweenthe F polymer and outside air, the fluorescent light enters the planenormal to these boundaries. Consequently, the fluorescent light does notrefract, so there is no problem caused by aberration. As describedabove, the surface of the filled F polymer 60 is molded so that thecross section forms part of the circle concentric to that of thecapillary, whereby the intensity of fluorescent light detected by themeasuring part (CCD 34) is increased, with the result that sensitivityis improved.

[0115] The resolution is also improved by molding the filled F polymer60 in such a way that the surface thereof has a predetermined curvedsurface. For example, a curved surface is formed in such a way that onecross section has a predetermined curve (an ellipse, hyperbolic curve,or circle where the central axis is different from that of thecapillary). This allows the F polymer 60 to work as a lens so that agreater amount of fluorescent light emitted from the test sample can befocused onto the measuring part 34-3. It should be noted that theproblem raised by aberration can be solved by forming the surface as anon-spherical lens or by providing the inspection part 34-3 with afilter.

[0116] As described above, the surface of the polymer 60 is formed tohave a predetermined curved surface, and the forward direction of thefluorescent light is controlled so that the intensity of the fluorescentlight entering the detection part is increased, whereby sensitivity canbe improved.

[0117] [Embodiment 5]

[0118]FIG. 10 is a side view representing a portion of a multi-capillaryarray including the irradiatable portions of capillaries of the array,according to an embodiment 5. In embodiment 5, the liquid filling thespace between capillaries exposed to the laser beam is not included inthe cell structure of the capillary array. It is held by the cellstructure that contains the liquid provided on the side of the capillaryarray electrophoresis apparatus proper. In this case, the capillary isdipped in the cell of the apparatus and the capillary is fixed inposition. Other features not described in particular are the same asthose in embodiment 1.

[0119] Except that the capillary array does not have a cell structure,the basic configuration of the irradiation part formed on the array base15 is the same as that of embodiment 1. Capillaries are arranged on thearray base 15 to ensure that all the capillaries 16 will contact thearray base 15 and the adjacent capillaries, and are bonded and fixed tothe array base 15 together with the holding plate.

[0120] The capillary array mounting section of the electrophoresisapparatus comprises a cell as a vessel to be filled with the F solution,fused silica windows 72 and 73 of the cell as irradiation parts passedby laser beams, a fused silica window 71 on the lower part of the cellas a fluorescent light transmission part, and a mounting referencesurface 41.

[0121] The electrophoresis apparatus is configured so that the capillaryarray is mounted to face downward. The relative position between thearray base 15 and electrophoresis apparatus can be adjusted by bringingthe surface 40 of the array base 15 in contact with the mountingreference surface 41.

[0122] The cell of the electrophoresis apparatus is filled with the Fsolution 19, and laser beams 24 and 25 travel in the F solution 19 inthe horizontal direction through the fused silica windows 72 and 73 ofthe cell. The capillary emits light downward, which is detected by thesame detection part as that of the embodiment 1 through the fused silicawindow 71 on the lower portion of the cell.

[0123] To prevent the bubble from entering the laser light path, thearray base 15 is provided with a hole 70. The hole 70 can be defined asformation of a hole through the array base 15. A similar effect can beachieved by forming a groove on the array base 15 positioned above theirradiation part. This allows the bubble in the vicinity of theirradiation part of the capillary to move upward, with the result thatthe bubble does not remain on the laser light path. In this embodiment,the irradiation part of the multi-capillary array is immersed in the Fsolution, so almost the same result of measurement as that in embodiment1 can be achieved, with the result that the sensitivity of theelectrophoresis apparatus can be improved.

[0124] [Embodiment 6]

[0125] In the embodiment 6, a polarizer element which transmits onlylaser light polarized in a direction and a half-wave plate element forrotating the polarization direction of the laser beam are properlyarranged in an electrophoresis apparatus where laser beams areirradiated from both sides of multiple capillaries, thereby avoiding orsuppressing the problem of laser oscillation being made unstable by thelaser light returning to the laser oscillator.

[0126]FIG. 11 is a schematic diagram representing the embodiment 6. Thecapillary array is configured in the same manner as that inembodiment 1. It indicates only the vicinity of the capillary arrayincluding the irradiatable part and laser light path, not the lasershutter or filter. The multi-capillary array electrophoresis apparatusaccording to the present embodiment comprises a capillary array havingthe same configuration as embodiment 1, an irradiatable part forapplying two bundles of laser beams propagating multiple capillaries andadjusting the traveling direction of these two bundles of laser beams soas to make them opposite to each other, and a light cut-off part forensuring that the laser beams having passed through the capillary arraydo not return to the laser properly.

[0127] The light cut-off part comprises a laser 87 as a light source forapplying a laser beam 80 as coherent light, a half-mirror or beamsplitter 81 capable of splitting one bundle of laser beams 80 into twoequal parts to create two bundles of laser beams 24 and 25, a mirrors 91for changing the traveling direction of laser light, and condensinglenses 83 and 84. The mirror, half-mirror or lens may be interposed inthe path of the laser light. Alternatively, two separate laser lightsources can be used instead of the beam splitter.

[0128] The light blocking part consists of half wave plates 88 and 89(λ/2 plate, mica wave plate, etc.) as an element capable of changing thepolarization direction of the transmitting light) and a polarizer 90capable of transmitting only a predetermined polarized beam.

[0129] The laser beam 80 launched by the laser 87 is split into twosubstantially equal parts by the half mirror 81. These two laser beam sare introduced to the capillary array 82 from both sides of capillaryarray, where light reflected by the half mirror 81 is a laser beam 24,while the transmitted light is a beam 25. The condensing lens of thelaser beam 24 is a condensing lens 83, while the condensing lens of thelaser beam 25 is a condensing lens 84. Hereafter the capillary locatedat the end of the array where laser beam 24 is introduced will be calledthe first capillary 85, and the capillary where laser beam 25 isintroduced will be called the 96th capillary 86.

[0130] The laser beams 24 and 25 are located in a plane surface(hereinafter abbreviated as “array surface”) including the center axisof each of 96 capillaries and are introduced perpendicularly to thecapillary. Laser beams 24 and 25 are coaxial to each other. The opticalaxis has been adjusted to ensure that one of them having passed throughthe capillary passed coaxially with the other incident laser beam to goback the laser 87.

[0131] Laser beams 24 and 25 are originally straight polarized beams,and their direction of polarization is vertical to the capillary axiswhen the half-wave plate and the polarizer are not placed along thelaser beam excitation light paths. In the aforementioned configuration,the light reflected from the capillary array or the light havingtransmitted through the capillary array returns to the laser, causingsuch a problems as unstable laser oscillation and fluctuation of signalbase line. When the halfwave plate and the polarizer are not used, eachof the intensities of the transmitted light returning and that of thereflected light returning is about 6 percent of the incident lightintensity, respectively.

[0132] To minimize this returned light, half wave plates 88 and 89 suchas a crystal λ/2 plate or mica wave plate were placed as an elements forrotating polarization direction on the capillary side of the lasercondensing lens for laser beams 24 and 25 from both upper and lowerdirections. The sequence of the optics in the order of the laser beamsbeam paths can be the laser, the half-mirror, the polarizer, thecondensing lens, the half-wave plate, and the capillary array. In caseswhere two laser beams are used to irradiate respective sides of acapillary array, two 10 polarizers and two half-wave plates can be usedalong with a single polarizer.

[0133] According to various embodiments, the installation of thepolarizing filter and polarization rotating element is not limited tothe above-mentioned installation. For example, according to variousembodiments both the polarizing filter and the polarization rotatingelement can be installed on the capillary side of the branching point.In this case, two each of the respective optical elements can be used.The polarization rotating element can be installed on the laser side ofthe branching point. In this case, a single polarization rotatingelement is required.

[0134] The sequence of the condensing lens and the half-wave plate canbe exchangeable. The rotation angles of the polarizer and the half-waveplate around the optical axis can be adjusted as follows:

[0135] The rotation angle of the half-wave plate can be adjusted so thatthe angle of rotation for polarization will be 45° to the capillary axisand the polarization direction for the two incident laser beam is 90°.The angle of the polarizer can be adjusted in such a way that theintensity of the transmitted light from the laser through the half-waveplate can be maximized.

[0136] The polarization direction of the incident light can be turned anadditional 45° by passing through the second half-wave plate afterpropagating the capillary array. Because the total rotation angle is90°, the laser beams that propagate the capillary array and the twohalf-wave plates can be blocked by the polarizer before those beams getback to the laser oscillator. It should be noted that the rotation angleof the half-wave plate and polarizing direction of the polarizer is notstrictly limited to the aforementioned figures, but large tolerance isallowed if the intensity of returned light is suppressed to a level thatdoes not cause laser unstabilization.

[0137] In the present embodiment, the half-wave plate can be arranged onthe capillary array side rather than on the split point, and thepolarizer can be arranged on the laser side rather than on the splitpoint. The polarizer placed in the vicinity of the laser has its angleadjusted to ensure that the intensity of laser light at the position ofcapillary array is maximized. The light that has come back along theloop-formed light path after passing through the capillary array has itsdirection of polarization turned 90°. As a result, the intensity of thetransmitted light of the polarizer is suppressed for the returned light.

[0138] The arrangement of the polarizer and the half-wave plate is notrestricted to the aforementioned one. For example, both the polarizerand the half-wave plate may be placed on the capillary side rather thanon the split side. In this case, two of each of the respective opticalelements can be used. Further, the polarizer can be placed on the laserside rather than on the split side. In this case, only one polarizer isneeded. In this manner, the laser beam launching from the laser 87properly passes through the polarizer (angle adjusted to maximize thetransmitted light) and is split into two parts by the half mirror. Afterhaving passed through the half-wave plate, laser light is introduced tothe capillary array from two directions. The polarized light of thelaser vertical to the capillary axis is turned 45° by the half waveplate 88, and enters the capillary array at an angle of 45° with respectto the capillary axis. On the aforementioned light path, the polarizingdirection of the two upper and lower laser beams can be vertical to eachother at the point of the capillary array. The intensity of the signallight from inside the capillary depends on the polarization direction ofthe incident laser beams but two upper and lower laser beam bundles haveangles of 45° with respect to the capillary axess, so the intensity ofthe signal light of 96 capillaries is distributed with symmetrical upperand lower parts.

[0139] Laser light having propagated the capillary array passes throughthe half-wave plate (polarized light turned in the same direction as thefirst half-wave plate). The half-wave plates arranged on both sides ofthe capillary array are set to rotate the polarization direction of thelaser light in the same direction. So the laser light emitted from oneend of the capillary passes through the capillary; then the direction ofpolarization is turned again by the half-wave plate, and is orientedsubstantially perpendicular to the initial polarization direction of thelaser light.

[0140] Then the light enters the polarizer via the half mirror. Here thesecond polarizer is the same as that of the first polarization filter.The returned light enters from the opposite direction. However, thepolarization direction of return light is turned 90°. In other words,the polarized light of the laser beams 24 in the direction vertical tothe capillary axis is turned 45° by the half wave plate 88, and entersthe capillary array with the polarization direction being at an angle of45° to the capillary axis. After laser beams 24 have passed through 96capillaries, the polarization of the beams is turned a further 45° bythe half wave plate 89. The laser beams 24 have a polarization directionturned a total of 90° by passing through the two half wave plates 88 and89. Similarly, the transmitted light of laser beam 25 has itspolarization direction turned by 90°. The transmission light enters thepolarizer. The angle of this polarizer can be adjusted to maximize theintensity of light coming from laser side, and the light on its way ofreturning to the light path through the capillary array has itspolarization direction turned by 90°. So the polarizer is adjusted sothat the intensity of the transmitted light having returned will beminimized.

[0141] Consequently, it cannot pass through this polarizer and cannotreach the laser head in a large amount. This prevents the returned lightfrom reaching the laser. In the step of passing through the 96capillaries, the linearly polarized light is disturbed and the linearlypolarized components are reduced about 25 percent compared to the onebefore passing through the capillaries. However, the present inventionhas succeeded in reducing the return of transmitted light by 75 percent.

[0142] The present embodiment solves the problem where the light havingpassed the capillary array returns to the laser oscillator todeteriorate laser oscillation stability, and provides relatively stablelaser oscillation.

[0143] [Embodiment 7]

[0144] According to various embodiments, the angle of laser lightentering the capillary can be made non-vertical or non-perpendicular tothe multi-capillary array. This angling can be included inelectrophoresis apparatus where excitation is directed at the array fromone or both sides of the array.

[0145]FIG. 12 is a schematic view of the embodiment 7. The configurationof this embodiment is basically the same as that of the embodiment 6,except for the optical axis of the irradiation part. However, the laserlight is introduced into the aforementioned irradiatable portion at anangle of about 2° deviated from normal with respect to the axial lengthsof the irradiatable portions of the capillaries. Further, a pinholeplate 97 can be provided as a light selection member. This lightselection member comprises an opening that allows transmission of thelaser light traveling from the light source to the capillary, and apartition for blocking of the returned laser light traveling from thecapillary to the light source.

[0146] Laser beams 24 and 25, which can also be referred to herein aslaser beam bundles, are propagated the array surface, and enter thecapillary at an angle 2° deviated from the normal. Laser beams 24 and 25can be coaxial with each other when they irradiate the capillary array.The optical axis of the beams can be adjusted in such a way that one ofthe laser beams that passes through the capillary travels coaxially withthe other laser beam, and goes back to the laser 87. As a result, thebeams 95 and 96 reflected from the capillary or cell by laser beams 24and 25 travel along optical axes different from the optical axes of theincident lasers shown in FIG. 12.

[0147] A pinhole plate 97 having a 1.4 mm-diameter pinhole as a lightselection means that does not interfere with the laser beam coming fromlaser side and, at the same time, that does not transmit the laser lightreflected from the capillary, can be installed at a position close tothe laser outlet. The laser light from the laser 87 passes through thepinhole, but the reflected light cannot pass through it. This makes itpossible to prevent the reflected beams 95 and 96 from returning to thelaser oscillator 87. Consequently, this solves the problem of the lightreflected from the capillary and cell returning to the laser oscillatorto cause instability of laser oscillation.

[0148] When this embodiment is combined with embodiment 6, the return ofthe transmitted light is reduced and according to the method ofembodiment 6, return of the reflected light is reduced according to themethod of the present embodiment, whereby stable laser oscillation canbe ensured.

[0149] [Embodiment 8]

[0150] According to present embodiment 8, the filling medium appliedaround the capillary can be formed into a predetermined curved surface,to ensure that fluorescent light emitted from the capillary is notdiverged when passing through the boundary of the filling medium.

[0151]FIG. 16 is a top view of an array portion showing an irradiatableportion of a capillary according to embodiment 8. Otherwise, theconfiguration is the same as that of the embodiment 3. As shown in FIG.16(a), the F polymer 60 as a filled medium is formed to have a convexsurface as viewed from the laser irradiation part 100 in the capillary.Here the “f#” of the fluorescent light collimating lens 31 is 1.8. Ifthe F polymer 60 has a plain surface (“b” in FIG. 16), signal light willrefract on the boundary 65 between air and F polymer 60, so only signallight within about ±11° on the cross section of the capillary can reachthe fluorescent light collimating lens 31, as illustrated.

[0152] In the meantime, if the F polymer 60 has a convex surface (“a” inFIG. 16), signal light within about ±11° to 15° on the cross section ofthe capillary reaches the fluorescent light-collimating lens, dependingon the curvature radius of the surface. As described above, theintensity of the fluorescent light coming from the capillary 16 can beincreased by forming the filled F polymer 60 to have a curved convexsurface.

[0153] To ensure an effective increase of the intensity of thefluorescent light, the center of the convex on the surface of the Fpolymer 60 can be aligned with the laser light axis. Since thefluorescent light emitted from the test sample travels in the directionvertical to the convex surface of the F polymer 60, there is no changein the traveling direction when passing through the convex surface(boundary surface). This also reduces the problem of aberrations at theCCD.

[0154] The sensitivity can also be improved by forming the surface ofthe filled F polymer 60 into a predetermined curve. For example, acurved surface is configured in such a way that a cross-section isshaped in a predetermined curve (an ellipse, hyperbola, or circle whosecenter is different from the laser light path). This allows a greateramount of fluorescent light to be converged by the CCD camera as adetection part, with a resultant increase in the intensity of thefluorescent light detected by the CCD. In other words, the F polymer 60will work as a lens and the traveling direction of the fluorescent lightcan be adjusted by forming the surface of the F polymer 60 around thecapillary to have a predetermined curve. It should be noted that theproblem of aberrations can be solved by forming such a lens to havemultiple focuses on the surface of the F polymer 60.

[0155] The surface of the F polymer 60 is not restricted to one incontact with air. It can refer to the surface in contact with the mediumhaving a refractive index different from that of the F polymer 60.Another medium having a different refractive index can be presentbetween the F polymer and capillary. This embodiment can be implementedsimultaneously with embodiment 4.

[0156] [Embodiment 9]

[0157] Embodiment 9 provides a method for forming a predetermined curvedsurface of the outer mold of a vessel covering the filling medium aroundthe capillary, thereby ensuring that the fluorescent light emitted fromthe capillary will not be diverged when passing through the surface ofthe vessel.

[0158]FIG. 17 is a top view representing the portion close to theirradiation part according to embodiment 9. Otherwise, the configurationis the same as that of embodiment 1. As shown in FIG. 17a, the surfaceof the cell cover 20 is convex, as viewed from the laser-irradiationpart 100 in the capillary. Assume that the “f#” of the fluorescentlightcondensing lens 31 is 1.8. When the surface of the cell cover 20has a plane surface (FIG. 17b), signal light is refracted by theboundary 101 between air and cell cover 20, so only the signal lightwithin the range of about ±11° on the cross-section of the capillaryreaches the fluorescent light collimating lens 31, as illustrated.

[0159] When the cell cover 20 has a convex surface as shown in FIG. 17a,the signal light within the range of about 11° to 15° on the capillarycross-section reaches the fluorescent light collimating lens, dependingon the curvature radius of the surface profile.

[0160] As described above, it is possible to increase the intensity ofthe fluorescent light from the capillaries 16 to be detected by formingthe cell cover 20 to have a convex surface. To ensure an effectiveincrease of the intensity of the fluorescent light, the center of thecircular arc of the convex on the surface should preferably be alignedwith the laser light axis. Further, fluorescent light can be convergedby the CCD camera as a detection part and the intensity of thefluorescent light can be increased by forming the curved surface of thecell cover to have a smaller curvature radius. In other words, a vesselwith a cell cover will work as a lens and the traveling direction of thefluorescent light can be adjusted by forming the surface of the vesselwith the cell cover to have a predetermined curve.

[0161] The surface of the cell cover is not restricted to the one incontact with air. It can refer to the surface in contact with the mediumhaving a refractive index different from that of the vessel with thecell cover. Another medium having a different refractive index can bepresent between the cell cover and the filling medium forming theboundary.

[0162] [Embodiment 10]

[0163] According to embodiment 10, a multi-capillary array having aplanar surface can be provided with a cylindrical lens where one side isplanar and the other side is curved, whereby the function of the convexsurface of the cell cover in embodiment 9 is performed by thecylindrical lens 102 mounted on the apparatus.

[0164]FIG. 18 is a top view representing the portion close to thelaser-irradiatable part of embodiment 10. In this embodiment, thecylindrical lens 202 mounted on the electrophoresis apparatus properlycovers the cell cover of the multi-capillary array according to thepresent embodiment 1. Otherwise, the configuration is the same as thatof the embodiment 1.

[0165] The function of the convex surface in the embodiment 9 can beperformed by the cylindrical lens 202 mounted on the apparatus, so aglass plate with plane surface can be used as the cell cover of thecapillary array as a consumable component. Further, since thecylindrical lens 202 is mounted on the apparatus, the center of theconvex surface of the cylindrical lens 202 is aligned with the laserlight axis. This provides an advantage that the intensity of the laserbeams does not depend on the capillary array mounting accuracy.

[0166] [Embodiment 11]

[0167]FIG. 19 contains a front view (19 a) representing a portion of amulti-capillary array including the laser irradiatable part and across-sectional view (FIG. 19b) taken along line A-A′ of the front viewof FIG. 19a. In this embodiment, a background light shielding orblocking member having a detection window allowing passage of thefluorescent light emitted from the sample in a capillary is arrangedover the capillaries placed in parallel on the fused silica-made arraybase 15 for the irradiatable portion. Otherwise, the configuration isthe same as that of embodiment 1.

[0168] All he 96 capillaries 16 are arranged on the array base 15 andare bonded and fixed on the array base 15 together with the siliconplate 101. A detection window partitioned by a protective guard 102 anda V-groove 104 for positioning the capillaries 16 are formed on thesilicon plate 101 by silicon anisotropic etching technology. Since thecapillaries 16 fit in the Vgroove, they can be arranged at apredetermined interval with a high degree of precision, and thedetection window 103 partitioned by the protective guard 102 and thecapillary 16 can be easily positioned.

[0169] Further, a silicon plate-positioning guide 105 is formed on thearray base 15. This is within the permissible detection range of themeasuring part. In other words, if all the capillaries 16 are locatedinside the silicon plate-positioning guide 105, all the capillaries 16will be within the permissible detection range of the detection part.The capillary 16 and array base 15 can be easily positioned with eachother by the silicon plate positioning guide 105 formed on the arraybase 15.

[0170] The capillaries 16 can be configured in such a way that the fusedsilica tube 18 can have an inner diameter of 50 μm and an outer diameterof 126 μm covered with a 12 μm thick polymer coating. The total outerdiameter can be 150 μm. The capillaries can be filled with an aqueouspolymer solution (refractive index: 1.41) as a DNA separation medium. Inthe irradiation part, the polymer coating can be removed, and the fusedsilica tube 18 can be exposed.

[0171] When exposed to laser light, part of the irregularly reflectedlaser light irradiates the polymer coating of the capillary 16 toproduce fluorescent light, or the part of the fluorescent light emittedby the DNA sample is irregularly reflected. When the fluorescent lightfrom the polymer coating and the light irregularly reflected from theDNA sample are received, the signal to noise ratio will be reduced dueto increase of the background light, with the result that detectionaccuracy is deteriorated.

[0172] However, the desired laser beam passes through the detectionwindow 103, but the background light is cut off by the silicon plate,whereby the increase of background light can be avoided. Further, toensure that the light reflected from the array base 15 does not passthrough the detection window 103 and is not received by the detectionpart, a reflection preventive film 106 is formed on the array base 15.This further reduces the background light, so the detection accuracy canbe further improved.

[0173] The irradiatable portions of the capillaries can be surrounded byF solution 19. The F solution 19 can be completely sealed by the fusedsilica-made cell cover 20, array base 15, and adhesive for bonding themtogether. To prevent the cell sealing structure from being damaged bythe volume expansion of the F solution 19 resulting from temperaturechange, the sealing structure can contain a highly compressible foam 107having a foaming magnitude of 30 times (foam accounting for about{fraction (29/30)}th of the total volume). The volume expansion of the Fsolution 19 is 0.0012 mm³/mm³° C. If the difference between thecapillary array storage temperature (room temperature: 25° C.) andworking temperature (60° C.) is assumed as 35° C., then increase involume resulting from temperature rise (35° C.) of the F solution 19from the storage temperature to working temperature is about 0.04mm³/mm³ (about 4%). The size of the foam 107 is assumed to be about 10percent of the cell volume.

[0174] The foam 107 can be arranged in the groove formed on the arraybase 15 so that it is sandwiched between the array base 15 andcapillaries 16. Further, the foam 107 can be excited by scatteredexcitation light, but is placed at a hidden position by the siliconplate 101. This avoids increase of the background light due to thefluorescent light from the foam 107. Further, the foam 107 can be placedin a hole 109 for pouring the F solution in the sealed part of the cellas a cover to block the hole. This eliminates the need of specialprocessing only for the foam 107 on the array base 15.

[0175] To prevent bubbles from entering the laser light path, absence ofbubbles inside the cell can be ensured, but it is not easy to eliminatebubbles completely. Even if a bubble has entered the cell filled with Fsolution, the fused silica-made bubble-eliminating block 23 is formed inthe cell in order to ensure that the buddle prevents the bubble fromentering the laser light path.

[0176] To maintain constant the angle between the incident laser beamand the laser incident surface of the cell, a guide 108 can be used as acell cover-positioning groove formed on the array base 15. This ensureseasy and reliable positioning on the array base 15. This configurationprovides a capillary array having a high signal to noise ratio andreduced background light.

[0177] Legend of the Reference Signs in the Drawings

[0178]1. Capillary array, 2. Negative electrode, 3. Buffer on negativeelectrode side, 4. Gel block, 5. Connection to a gel block, 6. Valve, 7.Ground electrode, 8. Irradiatable portion or part, 9. Laser beam, 10.Syringe, 11. Air-circulating oven, 11-1. Light source, 11-2. Highvoltage power source, 11-3. Sample introduction part, 11-4. First buffervessel, 11-5. Fluid medium injection part, 11-7. Second buffer 11-6.Detection part, 12. Buffer on ground electrode, 15. Array base, 16.capillary, 17. capillary holding plate, 18. fused silica tube, 19.3M-made fluorine solution containing “Fluorinert” FC43 for filling thespace around the capillaries, 20. Quartz-made cell cover, 20-2. Bubblestorage space, 21. Adhesive for fixing the cell cover, array base andcapillary in position, 22. Bubble, 23. Fused silica-made bubbleeliminating block for preventing bubbles from entering the laser lightpath, 24. and 25. Laser beams, 31. Fluorescent light collimating lens,32. Grating, 33. Focus lens, 34. CCD, 34-2. Detecting mechanism, 35.Emission from capillary, 36. Luminous flux formed of light emitted fromthe capillary converted into parallel light by a fluorescent lightcollimating lens, 40. Reference surface P for array base, 15, 40-2.Reference plane surfaces for arranging the capillary array, 41. Mountingreference surface P′ on the array irradiatable portion or part mountingsection, 44. Holding rod, 45. Spring, 46. Reference surface Q verticalto the surface P of the array base and parallel to the X-axis, 47. and48. Mounting reference lines in contact with reference surface Q of thearray base on the array irradiatable portion or part mounting section,50. Surface R of the fused silica surface of cell cover passed by laserlight, 51. Surface S of the quartz surface of cell passed by laserlight, 51-6. Excited light transmission part, 51-7. Laser beamtransmission part, 51-8. Pressure part A, 51-9. Pressure part B, 51-10.Spring, 51-11. Mounting section cover, 52. Surface T of the fused silicasurface of cell passed by laser light, 53. Surface Y of the quartzsurface of cell passed by laser light, 54. A point of the portion incontact with F solution of the array, 55. A point of the portion incontact with F solution of the cell cover, 60. Fluorinated polymer forcovering the irradiation part of capillary array, 60-2. Irradiatableportion or part, 61. and 62. Polymer block located outside thecapillaries on both ends to intercept fluorinated polymer, 65. Boundarybetween air and F polymer 60, 70. Drilled hole on the array base forpreventing entry of bubbles on the laser light path, 71. Quartz windowfor detecting fluorescent light on the bottom of the cell, 72. and 73.fused silica windows for laser beam transmission, 80. Laser beam, 81.Half mirror, 82. Capillary array, 83. and 84. Laser light condensinglens, 85. and 86. End capillary passed by laser beam, 87. Laser, 88. and89. Half wave plates, 90. Polarization filter, 91. Mirror, 95. and 96.Laser beams reflected by capillary and cell, 97. Pinhole plate, 101.Silicon plate, 102. Protective guard, 103. Detection window, 104.V-groove, 105. Silicon plate positioning guide, 106. Reflectionpreventive film, 107. Foam, 108. Cell cover positioning guide, 109. Fsolution injection hole, 202. cylindrical lens.

What is claimed is:
 1. A multi-capillary array including: a plurality ofcapillaries that are filled with a separation medium, each capillary ofthe plurality having a respective first portion into which a sample canbe introduced, and a respective light-irradiatable portion that iscapable of being irradiated with excitation light, wherein the pluralityof light-irradiatable portions are arranged in a row on a plane and arecapable of being simultaneously irradiated with an excitation lightsource, and a substance that has a refractive index that is higher thanthe refractive index of air and lower than the refractive index ofwater, wherein the substance is disposed between two or more adjacentlight-irradiatable portions.
 2. The multi-capillary array according toclaim 1, wherein the substance comprises water, an aqueous solution, afluorine-containing compound, or a combination thereof.
 3. Themulti-capillary array according to claim 1, wherein the substancecomprises a fluorine-containing compound that is a liquid at roomtemperature and atmospheric pressure.
 4. The multi-capillary arrayaccording to claim 1, wherein the substance comprises afluorine-containing polymer.
 5. The multi-capillary array according toclaim 1, wherein the substance comprises a fluorine-containing compoundhaving a refractive index of from about 1.29 to about 1.32.
 6. Themulti-capillary array according to claim 1, wherein the number ofcapillaries in the plurality of capillaries is about 24 or greater. 7.The multi-capillary array according to claim 1, wherein thelight-irradiatable portions of the capillaries are in contact with oneanother, arranged side-by-side in a planar array.
 8. The multi-capillaryarray according to claim 1, wherein the light-irradiatable portions ofthe capillaries are spaced from one another, arranged side-by-side in aplanar array.
 9. A device comprising: a multi-capillary array includinga plurality of capillaries filled with a separation medium, eachcapillary of the plurality having a respective first portion into whicha sample can be introduced, and a respective light-irradiatable portion,wherein the plurality of light-irradiatable portions are arranged in arow on a plane and a substance is disposed between two or more adjacentlight-irradiatable portions, the substance having a refractive indexthat is higher than the refractive index of air and lower than therefractive index of water; an excitation light source capable ofemitting excitation light to simultaneously irradiate the plurality oflight-irradiatable portions; and a detector capable of detecting lightemitted by samples disposed within the light-irradiatable portions uponirradiation with excitation light.
 10. The device according to claim 9,further comprising a power supply capable of supplying a voltage to acurrent path that includes the first portions and the light-irradiatableportions.
 11. The device according to claim 9, wherein said substancecomprises water, an aqueous solution, a fluorine-containing compound, ora combination thereof.
 12. The device according to claim 9, wherein saidsubstance comprises a fluorine-containing compound that is a liquid atroom temperature and atmospheric pressure.
 13. The device according toclaim 9, wherein said substance comprises a fluorine-containing polymer.14. The device according to claim 9, wherein said substance comprises afluorine-containing compound having a refractive index of from about1.29 to about 1.32.
 15. The device according to claim 9, wherein thenumber of capillaries in the plurality of capillaries is about 24 orgreater.
 16. The device according to claim 9, further comprising abackground light-blocking member disposed between the detector and theplurality of capillaries, wherein the background light-blocking memberhas a detection window that allows light emitted from samples in therespective light-irradiatable portions to pass through.
 17. A devicecomprising: a multi-capillary array including a plurality of capillariesthat are filled with a separation medium, each capillary of theplurality having a respective first portion into which a sample can beintroduced, and a respective light-irradiatable portion that is capableof being irradiated with excitation light, wherein thelight-irradiatable portions are arranged in a row on a plane; a powersupply capable of applying a voltage to a current path that includes thefirst portions and the light-irradiatable portions; an excitation lightsource capable of emitting excitation light in a direction toward theplurality of light-irradiatable portions to simultaneously irradiate thelight-irradiatable portions; a detector capable of detecting lightemitted by samples in the light-irradiatable portions upon irradiationof the samples with excitation light; and a vessel that holds a liquidhaving a refractive index that is higher than the refractive index ofair and lower than the refractive index of water, in areas between twoor more adjacent light-irradiatable portions, the liquid being locatedin a space which is interposed among the plurality of capillaries andthrough which the excitation light passes; wherein a temperaturegradient of the liquid, with respect to a direction that isperpendicular to both an axial direction of the light-irradiatableportions and the direction of travel of the excitation light from theexcitation light source, is substantially zero.
 18. A device comprising:a plurality of capillaries filled with a separation medium, eachcapillary of the plurality having a respective first portion into whicha sample can be introduced, and a light-irradiatable portion that iscapable of being irradiated with excitation light; a vessel thatincludes a first flat-plate part on which a plurality of thelight-irradiatable portions are arranged in a row, and a secondflat-plate part, the vessel holding a liquid having a refractive indexthat is higher than the refractive index of air and lower than therefractive index of water, in areas between two or more adjacentlight-irradiatable portions, and wherein the light-irradiatable portionsare disposed in a space between the first flat-plate part and the secondflat-plate part; a power supply capable of supplying a voltage to acurrent path that includes the first portions and the light-irradiatableportions; an excitation light source capable of emitting excitationlight that passes through the plurality of light-irradiatable portions;a detector capable of detecting light that is emitted by samples in thelight-irradiatable portions upon excitation with excitation light; and atemperature control unit to control the temperature of the firstflat-plate part to be higher than the temperature of the secondflat-plate part.
 19. A device comprising: a multi-capillary arrayincluding a plurality of capillaries that are filled with a separationmedium, each capillary of the plurality having a respective firstportion into which a sample can be introduced, and a respectivelight-irradiatable portion that is capable of being irradiated withexcitation light, wherein the light-irradiatable portions are arrangedin a row on a plane; a power supply capable of supplying a voltage to acurrent path that includes the first portions and the light-irradiatableportions; an excitation light source capable of emitting excitationlight in a direction toward the plurality of light-irradiatable portionssimultaneously; a detector capable of detecting light emitted by samplesin the light-irradiatable portions upon irradiation with excitationlight; and a sealed vessel that contains a liquid in areas between twoor more adjacent light-irradiatable portions, and that contains a gas;wherein the multi-capillary array includes a bubble-accommodating spacethat is capable of accommodating the gas, and the bubble-accommodatingspace is provided in a position through which excitation light, emittedfrom the excitation light source, does not pass.
 20. A devicecomprising: a multi-capillary array including a plurality of capillariesthat are filled with a separation medium, each capillary of theplurality having a respective first portion into which a sample can beintroduced, and a respective light-irradiatable portion that is capableof being irradiated with excitation light; and a sealed vessel includingan interior containing a foam material and through which thelight-irradiatable portions pass, wherein the foam material is disposedbetween two or more adjacent light-irradiatable portions in the sealedvessel.
 21. The device according to claim 20, wherein the sealed vesselincludes a liquid injection port from where foam is injected into theinterior of the sealed vessel.
 22. A device comprising: amulti-capillary array including a plurality of capillaries that arefilled with a separation medium, each capillary of the plurality havinga respective first portion into which a sample can be introduced, and arespective light-irradiatable portion that is capable of beingirradiated with excitation light, the plurality of capillaries beingarranged in a row on a plane; an excitation light source capable ofproviding excitation beam paths that pass through the light-irradiatableportions of the plurality of capillaries; a detector for detectingemission beams emitted by samples in the light-irradiatable portionsupon irradiation of the sample with excitation light; and alight-transmitting medium disposed between two or more adjacentlight-irradiatable portions and being transmissive of excitation lightgenerated by the excitation light source; wherein the light-transmittingmedium has a shape including a curved surface disposed along an emissionbeam path between the light-irradiatable portions and the detector. 23.The device according to claim 22, wherein the cross-sectional shape ofthe curved surface is circular and centered on an intersection betweenthe light-irradiatable portions and the excitation light.
 24. The deviceaccording to claim 22, wherein a cross-sectional shape of the curvedsurface is a circle, ellipse, or hyperbolic curve.
 25. A devicecomprising: a multi-capillary array including a plurality of capillariesthat are filled with a separation medium, each capillary of theplurality having a respective first portion into which a sample can beintroduced, and a respective light-irradiatable portion that is capableof being irradiated with excitation light; a detector for detectingemission beams emitted by samples in the light-irradiatable portionsupon irradiation with excitation light; and a vessel that holds a liquidhaving a refractive index that is higher than the refractive index ofair, and through which passes the light-irradiatable portions; whereinthe vessel includes a curved surface disposed along an emission beampath between the light-irradiatable portions and the detector.
 26. Adevice comprising: a multi-capillary array including a plurality ofcapillaries arranged in a row on a plane and filled with a separationmedium, each capillary of the plurality having a respective firstportion for introducing a sample, and a respective light-irradiatableportion capable of being irradiated with excitation light; a firstsource of first excitation light beams, disposed in a position to emitfirst excitation beams along a beam path through the light-irradiatableportions; and a first polarizing plate disposed along an excitation beampath between the first excitation light source and the multi-capillaryarray.
 27. A device according to claim 26, further comprising a secondsource of second excitation light beams, and a second polarizing plate,wherein the source of the first excitation light beams is disposed in aposition to emit the first excitation beams in a first direction throughthe light-irradiatable portions, and the second source of secondexcitation light beams is disposed in a position to emit secondexcitation beams in a second direction that is substantially opposite tothe first direction and through the light-irradiatable portions, thesecond polarizing plate being disposed along a second excitation beampath between the second source of excitation light beams and themulti-capillary array.
 28. The device according to claim 27, wherein thefirst source of first excitation light beams and the second source ofthe second excitation light beams comprise separate light sources. 29.The device according to claim 28, wherein the first source of firstexcitation light beams and the second source of second excitation lightbeams, comprise separate laser light sources.
 30. The device accordingto claim 27, further comprising a half-wave plate disposed along anexcitation beam path between the first polarizing plate and themulti-capillary array.
 31. The device according to claim 27, wherein thefirst source of first excitation light beams and the second source ofsecond excitation light beams, comprise the same excitation lightsource, and a beam splitter is disposed along a beam path between theexcitation light source and the multi-capillary array.
 32. The deviceaccording to claim 31, wherein the excitation light source comprises asingle laser excitation light source.
 33. The device according to claim31, further comprising: a first half-wave plate disposed along anexcitation light beam path that transmits through the beam splitter, anddisposed between the beam splitter and the multi-capillary array; and asecond half-wave plate disposed along an excitation light beam path thatis reflected by the beam splitter, and disposed between the beamsplitter and the multi-capillary array.
 34. The device according toclaim 31, wherein excitation light transmitted through the beam splitteris directed along a first beam path toward the multi-capillary array,and excitation light reflected by the beam splitter is directed along asecond beam path toward the multi-capillary array, and wherein the firstand second beam paths travel in directions substantially opposite to oneanother as they respectively pass through the multi-capillary array. 35.The device according to claim 30, wherein the half-wave plate rotatesthe polarization of excitation light emitted from the first excitationlight source, about 45°.
 36. The device according to claim 26, whereinthe light-irradiatable portions extend along respective axial lengths ofthe capillaries, and excitation light from the excitation light sourceis directed toward the light-irradiatable portions at an angle less than90° or greater than 90° relative to the axial lengths of thelight-irradiatable portions.
 37. The device according to claim 26,further comprising a detector capable of detecting light emitted bysamples in the light-irradiatable portions upon irradiation withexcitation light, wherein the multi-capillary array further includes abarrier that blocks excitation light that is reflected by thelight-irradiatable portions in a direction toward the detector.
 38. Adevice comprising: a sealed vessel that includes a multi-capillary arrayincluding a plurality of capillaries that are filled with a separationmedium, each capillary of the plurality having a respective firstportion into which a sample can be introduced, and a respectivelight-irradiatable portion that is capable of being irradiated withexcitation light, the light-irradiatable portions being arranged in arow on a reference plane, and a substance contained in the sealed vesseland disposed between two or more adjacent light-irradiatable portions,wherein the substance has a refractive index that is higher than therefractive index of air and lower than the refractive index of water,and the sealed vessel includes a first surface on a first plane that issubstantially parallel to the reference plane, and a second surface on asecond plane that is substantially perpendicular to the first plane; anda platform including a multi-capillary array attachment part forattaching the sealed vessel to, and detaching the sealed vessel from,the platform, the multi-capillary array attachment part including afirst attachment reference face that contacts the first surface, and asecond attachment reference face that contacts the second surface. 39.The device according to claim 38, wherein the reference plane and thefirst plane are on the same plane.
 40. The device according to claim 38,further comprising an excitation light source, wherein excitation lightfrom the excitation light source is emitted in a direction through thesecond plane.